000 AXNT20 KNHC 082337 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Mon Aug 09 2021 Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 31N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1800 UTC surface analysis and satellite imagery through 2330 UTC. ...SPECIAL FEATURES... Low pressure of 1011 mb near 13N53W is associated with an elongated area of low pressure that is located several hundred miles east of the Windward Islands. Latest satellite imagery shows scattered moderate to isolated strong convection in disorganized fashion from 09N to 14N between 51W-58W. The latest ASCAT satellite data pass show fresh to strong northeast winds north of the center. Environmental conditions are expected to be favorable to support some gradual development over the next few days, and this system could become a tropical depression while it moves west-northwestward at 8 to 13 kt. The disturbance is forecast to reach portions of the Lesser Antilles late Mon, and then move near the Virgin Islands and Puerto Rico on Tue, and near Hispaniola around the middle of this week. Interests in those areas should monitor the progress of this system, as it could bring locally heavy rainfall and gusty winds to portions of that area. This system has a medium chance of becoming a tropical cyclone during the next 48 hours. Please refer to latest Tropical Weather Outlook at hurricanes.gov for the latest information. ...TROPICAL WAVES... An eastern Atlantic tropical wave has its axis extending from near 03N31W to 12N32W and to 20N30W. It is moving westward at 10-15 kt. Only isolated showers and thunderstorms are seen within 30-60 nm west of the wave from 03N to 06N. A central Atlantic tropical wave has its axis along 49W/50W from 03N to 21N. Isolated showers and thunderstorms are within 180 nm either side of the wave from 08N to 11N. An eastern Caribbean tropical wave has its axis along 66W, south of 21N, moving westward at 10-5 kt. Latest ASCAT data depicted fresh to locally strong trades from 16N to 19N and between 60W-66W. Scattered showers and isolated thunderstorms are east of the wave north of 12N. This activity extends to portions of the Lesser Antilles. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coast of Senegal near 13N17W to a 1014 mb low pressure center that is near 15N27W and to 11N34W to a 1012 mb low pressure center near 14N45W, then to the Special Features 1011 low pressure center near 13N53W and to 10N58W. Aside from convection described above under the Special Features and Tropical Waves sections, scattered moderate to isolated strong convection is within 120 nm north of the monsoon trough between 46W-48W. Scattered moderate convection is within 120 nm northwest of the monsoon trough between 56W-58W. ...GULF OF MEXICO... The Gulf of Mexico remains in the SW flank of the subtropical ridge positioned near the Azores. This keeps the region in an environment of a relatively weak pressure gradient. Isolated showers and small thunderstorms are noted east of 88W, and from 21N to 25N and between 88W-94W. Scattered moderate convection is over the northwest and western sections of the Yucatan Peninsula due to the typical thermal trough found there. Fairly tranquil weather conditions prevail across he rest of the basin. Moderate to occasionally fresh southeast to south winds are n the Bay of Campeche and over the western Gulf of Mexico, with 3-4 ft seas. Light to gentle anticyclonic winds and seas of 1-3 ft are prevalent elsewhere. For the forecast, moderate to fresh east winds will pulse off the NW Yucatan Peninsula into the Bay of Campeche every night through Tue night in association with a diurnal trough. Elsewhere, a weak surface ridge along 27N will dominate the Gulf waters over the next few days and drift northward to along 29N-30N Tue through Thu. ...CARIBBEAN SEA... Scattered broken moderate convection is noted within 150 nm of the coasts of SE Nicaragua, Costa Rica and Panama. This is in association with the East Pacific monsoon trough that crosses into the Caribbean Sea through S Costa Rica and W Panama. The rest of the basin enjoys tranquil weather conditions. ASCAT data from this afternoon showed fresh to locally strong winds are over the south-central Caribbean, especially within 100 nm of the coast of NW Colombia. Seas in the area are 6-8 ft. Moderate to fresh trades are noted in the north-central Caribbean and Gulf of Honduras, while light to gentle trades prevail in the NW and SE Caribbean. Seas of 4-6 ft are prevalent in the north- central Caribbean and Gulf of Honduras, while 2-4 ft seas are found elsewhere in the basin. For the forecast, fresh to strong trades will continue across the south-central Caribbean through tonight, then diminish significantly across most of the basin through Mon. Otherwise, moderate to fresh trade winds will prevail across all but NW portions Mon evening through early Wed. A strong tropical wave with very active weather is expected to move across the tropical Atlantic waters Mon and Mon night, across the NE Caribbean and adjacent Atlantic waters Tue and Tue night, and reach 75W late Thu. ...ATLANTIC OCEAN... An expansive 10290 mb Azores high pressure system is the dominant weather feature in the tropical Atlantic, allowing for fairly tranquil weather conditions outside of the deep tropics. An exception to the tranquil weather can be found off the NE Florida coast and N of the NW Bahamas due to a trough that extends from near 31N77W to just offshore Stuart, Florida. Isolated showers and thunderstorms are noted in the vicinity of this trough. Farther east, a weak surface trough extends from near 31N69W to 26N72W and another surface trough extends from near 31N59W to 26N63W. Both systems are only producing shallow showers, mainly east of the trough axis. Gentle winds are near these both of these troughs. Gentle to moderate anticyclonic winds are found W of 50W and N of 20N, and seas of 4-6 ft. Moderate to fresh NE-E winds prevail E of 50W and N of 20N, and seas of 6-8 ft. However, fresh to strong north winds and seas of 7-9 ft can be found off the coast of Morocco. Over the deep tropics south of 20N, the monsoon trough extends across the waters from the coast of Africa to near 55W. Moderate to fresh trades continue north of the monsoon trough, with gentle to moderate southwest to west monsoon flow south of the monsoon trough. Three low pressure centers are embedded within the monsoon trough. Two of which are presently being monitored for potential tropical cyclone development. Please see the latest Atlantic Tropical Weather Outlook for more information. For the forecast W of 65W, fresh winds will pulse north of Hispaniola, including the approaches to the Windward Passage tonight. Elsewhere, the Atlantic surface ridge associated with the Bermuda-Azores high will persist with axis well north of the area for the next several days. A tropical wave with active weather is expected to enter the SE waters Mon night, move across the northeastern Caribbean and adjacent Atlantic waters Tue and Tue night and reach the southeastern Bahamas early Thu. $$ Aguirre